mediaproxy: switch from deprecated /var/run to /run

  The FHS 3.0 [F] has deprecated /var/run in favor of /run. Current
  distributions have done so for a long time (for example in Debian
  since 6.0 “squeeze”), even though they provide a compatibility
  symlink from /var/run to /run. But software like systemd have
  started emitting warnings when using /var/run, for example for
  its PIDFile directive, which pollutes the logs.

src/modules/mediaproxy/doc/mediaproxy_admin.xml

@@ -184,15 +184,15 @@ modparam("mediaproxy", "disable", 1)
       <para>
         <emphasis>
           Default value is
-            <quote>/var/run/mediaproxy/dispatcher.sock</quote>.
+            <quote>/run/mediaproxy/dispatcher.sock</quote>.
         </emphasis>
       </para>
 
       <example>
       <title>Setting the <varname>mediaproxy_socket</varname> parameter</title>
         <programlisting format="linespecific">
 ...
-modparam("mediaproxy", "mediaproxy_socket", "/var/run/mediaproxy/dispatcher.sock")
+modparam("mediaproxy", "mediaproxy_socket", "/run/mediaproxy/dispatcher.sock")
 ...
         </programlisting>
       </example>

src/modules/mediaproxy/mediaproxy.c

@@ -191,7 +191,7 @@ static int mediaproxy_disabled = False;
 static str ice_candidate = str_init("none");
 
 static MediaproxySocket mediaproxy_socket = {
-		"/var/run/mediaproxy/dispatcher.sock", // name
+		"/run/mediaproxy/dispatcher.sock", // name
 		-1,									   // sock
 		500, // timeout in 500 miliseconds if there is no answer
 		0,   // time of the last failure